The present invention relates to a hardening unit with a hydrogen closed-cycle, designed for hardening elements of machines, mechanical devices and vehicles, under a pressure of hydrogen or hydrogen-containing mixture being higher than the atmospheric pressure.
From the U.S. patent specifications numbered: U.S. Pat. Nos. 4,867,808, 4,869,470, 5,630,322, there are known constructions of vacuum ovens, in which the quenching of a charge is carried out under a gas pressure higher than that of atmospheric pressure, with a continuous circulation and cooling of the quenching atmosphere consisting mostly of nitrogen, helium, hydrogen or a mixture of these gases. From the patent applications numbered: EP 1 211 329 and DE 102 51 486, there are known processes and systems for gas recycling in thermo-chemical treatments with the use of multi-stage systems of mechanical rotary and membrane pumps.
There are also known methods of accumulation and storage of hydrogen in combined forms as metal hydrides as well as accumulators for cyclic accumulation and release of hydrogen, while these hydrides are utilized mostly in motoring sector as fuels in combustion engines and fuel cells.
There are also known, from the U.S. patent specifications numbered: U.S. Pat. Nos. 4,225,320, 4,829,772 and 6,722,154, the systems of a hydrogen closed-cycle between two hydrides with different temperature-pressure equilibrium constants that utilize the heat of formation or hydride dissociation in the technical systems of gas heating, cooling and drying.
From the U.S. patent application No. US 2002/0025461, there is known also a unit for metal hydride charge regeneration, utilizing two metal-hydrides with different temperature-pressure equilibrium constants.